Early Otis King Calculator, serial 5272, model K (scales 414 and 423), Circa 1923

Otis King Calculator, serial 5272, model K cylindrical pocket slide rule with helical scales, made in England by Carbic Ltd., London. Does multiplication and division, with a scale approximately 170 cm long. Characterised by scale 414 on the bottom and scale 423 on top.

The inventor of this piece, Otis Carter Formby King (1876 to 1944), joined a manufacturing company, Carbic Ltd, in London for the production of the Otis King Calculator. It is estimated to have been first made in 1910. To use it, rotate the outermost and innermost cylinders, selecting the required numbers to be multiplied or divided on the logarithmic scales. Successive multiplication and division could be combined in 1 movement.

Some scraping down one side